How to Skip Converting to APFS When Installing macOS High Sierra

MacOS High Sierra includes the all new APFS file system, which is arguably one of the most significant new features introduced in the new Mac operating system update. Nonetheless it’s possible that some Mac owners with SSD volumes will want to not convert the existing HFS+ file system to APFS file system when installing macOS High Sierra. With a little command line magic, you can skip converting to APFS during the macOS High Sierra installation process if desired.

How to Install macOS High Sierra Without Converting to APFS File System

This is not recommended and should only be applicable to advanced users who have specific reasons to not want to convert a Mac to APFS. APFS is faster and offers better encryption, amongst other benefits, so it’s generally recommended to use APFS if the Mac supports it. APFS is currently only supported on SSD drives, with Fusion drives support for APFS soon to arrive in a future Mac software update.

How to Not Convert to APFS During macOS High Sierra Installation

By skipping APFS conversion of file system, macOS High Sierra will install with the longstanding HFS+ file system instead.

Download the MacOS High Sierra installer from the App Store as usual, making sure it’s within the /Applications/ directory*

Open the Terminal application, found in /Applications/Utilities/ (or from the Utilities screen menu options if booted from a USB boot installer)

Enter the following command syntax at the command line prompt:/Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/startosinstall --converttoapfs NO

Hit return key to start the macOS High Sierra install process with the –converttoapfs NO directive, thereby skipping the APFS conversion of existing file system

Mac users who ran the beta of macOS High Sierra may remember earlier versions of the beta builds had a toggle setting during installation to skip APFS conversion, but that option toggle is no longer available in the installer.

“When you install macOS High Sierra on the Mac volume of a solid-state drive (SSD) or other all-flash storage device, that volume is automatically converted to APFS. Fusion Drives, traditional hard disk drives (HDDs), and non-Mac volumes aren’t converted. You can’t opt out of the transition to APFS.”

Despite the Apple support article saying that you can’t opt out of the transition to APFS, it turns out that you can skip APFS if you choose to start the installer from the command line of Mac OS and give a directive to skip file system conversion. Outside of using the Terminal approach outlined above, or installing on an HDD or Fusion drive, there is no known other method to skip APFS.

Again, there is no benefit or particular reason for most users to skip APFS conversion. Skipping APFS file system on a Mac with a flash drive means the computer won’t see the potential performance boost offered by APFS with High Sierra. This is really only for advanced users who need to skip APFS for a specific reason, usually for networking or drive sharing compatibility purposes.

I am not a “nerd” and I do not understand what will happen to my backups online or on hard drives (not SSD) if I install High Sierra. Will those drives be readable and writable? or not? and if not, what do we do? I’d like to see an article that is easy to understand for all of us non-techie types. Thank you.

My Mac volume is a conventional HDD, so obviously APFS won’t install there. However, I have a couple of external SSDs which I connect to the Mac from time to time. When (and if…) I get round to installing High Sierra, will these drives be forced to change to APFS format ? Presumably that would render them unreadable by a non-High Sierra machine ?

Why would anyone want to make their network of Apple devices ( of various vintage ) plus all of their external drives etc. suddenly STOP working together? I’m staying with Sierra for the foreseeable future on my MBP TB, though I have installed High Sierra onto a 2008 Mac Pro with great success using the macOS High Sierra Patcher Tool .

Thanks Paul, will give that a shot. The entire reason I’m going this path is that I know APFS was disabled for RAID0 setups on SSD. I assume that HFS+ still works the same, and has been working well on Sierra (and previous incarnations) for a long time. I renamed my boot volume to “SSD”, so guessing it would be “–volume /SSD” for the install?

I’m one of those Mac Mini users who replaced the 2x500GB mechanical drives for 2x500GB SSD’s, and went RAID0 for speed/partition size :)

I also noticed that the MacPro (5,1) needs a firmware update. Question ? – Before installing 10.13, should one first update the firmware (via a separate drive) and then attempt the RAID 0 installation?

In AFPS’s defense, Apple claims their new file system demonstrates bugs in GCC’s make sub-system. But that system has been in place for years (like 20). So who’s to say who’s wrong. Apple and GCC are big players that probably will not except blame for a while. So…

Bootcamp is not working properly on APFS MacOS. Fron MacOS High Sierra you can enter windows using bootcamp, but the other way around isnt possible. Windows doesnt see the APFS disc. Shutdown and restart ALT is still working but is not ideal

Another thing I found out the hard way is that if you accidentally clear your partition table on APFS, there is virtually no way to recover it that I could find. Better have good backups. Did this while installing a linux os on external HD and mistakenly selected the wrong disk.

Just had a client with a formatted APFS drive that doodoo’d itself after power outage, without tools like Diskwarrior you don’t have a hope in heck of not spending a whole day sorting out this Bleeding Edge Technology.

Your goal is to change the true to false!!!
“how to use vi”
follow the instructions below very carefully:
– arrow down such that the cursor is at the ‘t’ in ‘true’
– press the Del key (fn+backspace) four times (this removes ‘true’)
– press i (this puts vi into insert mode)
– type ‘false’ (without the quotes)
– press Esc (this takes vi out of insert mode)
No other changes should be made.

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